Swim CSS & Zones

Default uses SCY (yards) and the classic 400/200 test. Back to Calculators

Inputs

Units follow pool type (25 yd default). Used for per‑length send‑offs.

CSS Pace

— /100
CSS (s/100) = (T400 − T200) / 2

CSS Speed

Speed at CSS (per 100 and per hour)

Send‑offs

Per 25 / 50 / 100 in your pool
ZonePace targetPer 25Per 50Per 100
Zones: Easy (CSS+12..+20), Endurance (CSS+6..+12), Threshold (CSS±3), VO₂ (CSS−4..−10), Sprint (<CSS−10). Adjust as needed.